The present invention relates to liquid sprayers and more particularly to sprayers of the aspirator type that proportionally mix a liquid with water under pressure and provide a spray of the liquid/water mixture.
Sprayers of this type are commonly employed to apply diluted solutions containing chemicals such as pesticides, fungicides, herbicides and fertilizers to lawns or garden foliage. Typically, sprayers of this type are attached to a garden hose that serves as a handle for the sprayer. The pressure of the water delivered through the hose is used to create a vacuum that causes the chemical to be aspirated into the water, to provide the diluted solution that is subsequently sprayed.
Different types of applications may have different requirements for the proportion of chemical that is mixed with the water, as well as the flow rate of the water, i.e. the number of gallons of water that are delivered per minute. For example, in lawn applications the desired mixture of water to chemical may be 60:1 and the flow rate might be 2.4 gallons/minute at a pressure of 50 psi. Garden sprayers may have a much higher mixture ratio of 24:1 but a lower flow rate that may be only 30% of that for lawn sprayers. In addition, the desired spray pattern may be different for various types of applications.
Consequently, sprayers for different types of applications may be constructed as separate units, each one being designed for the particular requirements of one application. Alternatively, a single sprayer can be designed for both lawn and garden applications, with appropriate controls for changing the flow rate, the water/chemical mixture ratio and the spray pattern. Examples of the latter type of sprayer are disclosed in U.S. Pat. Nos. 3,940,069 and 3,291,395. Basically, the sprayers disclosed in these patents include a rotatable control member that selectively positions different sized flowthrough bores and metering orifices in an operative position to control the water flow and mixing rates. In addition, they include a rotatable turret that enables different types of spray nozzles to be placed in fluid communication with the operative flowthrough bore to provide different spray patterns.
Although hose-end sprayers of the aspirator type are presently in widespread use and have met with a good deal of success, it is desirable to improve upon certain features thereof. More particularly, one limitation associated with heretofore known aspirator-type sprayers has been in the control that can be obtained over the spray pattern. In this context, a primary concern lies in the fact that these sprayers tend to drip during the spraying operation, either from the end of the nozzle through which the spray is emitted or at the interface of components in the sprayer. Since the chemicals that are often applied with these sprayers can be caustic or otherwise potentially harmful, any dripping thereof on the clothes of the person using the sprayer, for example, is highly undesirable.
In addition, misting or spurious emission of droplets can occur at the edges of the spray pattern. These types of emissions are undesirable from the standpoint that they can result in the deposit of the chemical in areas where it is not desired. For example, a strong pesticide might be deposited on a delicate ornamental plant located adjacent a shrub to be treated.
Further drawbacks associated with the limit on the control that could previously be obtained over the spray pattern relate to the non-uniformity of the spray and the variation in droplet size. Typically, larger droplets and heavier spray concentration would be found at the center of the pattern, resulting in an uneven application.
It has been determined that these limitations associated with the control of the emissions from the sprayer are in large part due to the fact that the liquid is vented to atmospheric pressure before the spray pattern is formed. Once the water and the liquid chemical are mixed through the action of the aspirator, they flow through a control bore, sometimes referred to as an eductor bore, while still under pressure. In the prior types of sprayers, a liquid stream is emitted from the bore into a chamber or other open space at atmospheric pressure, where the stream is allowed to expand. Thereafter, the stream strikes a deflector surface which forms it into the desired pattern. Since the pressure on the stream is reduced and it comes into contact with air prior to the time that it reaches the deflector surface, the degree of control that can be exercised over the spray pattern is practically limited.
Another feature of aspirator-type sprayers upon which it is desired to improve relates to the convenience and operating control that can be obtained with such devices. For example, in the sprayers illustrated in the previously noted patents, the spray of water is turned on and off at the sprayer through rotation of the control member about an axis that is parallel to the spray axis. This control of the spray typically involves a two-handed operation, since one hand must grasp the hose connected to the sprayer (or an extension of the sprayer that connects to the hose) to support and hold it steady while the other hand turns the control member.
Other sprayers have different types of control actuators but still require the same basic operation of rotating or pivoting the control through an arc to turn the spray on or off. This action can be somewhat cumbersome, and can cause the spray to be deposited in areas other than where it is desired. In other words the operator may point the sprayer in a direction other than where the spray is initially desired in order to be able to conveniently grasp it and rotate the control member.
Each of these rotatable actuators provides only two modes of control over the spray, i.e. on or off. They remain in either the on or off position unless actuated by the operator. If the person operating the sprayer should happen to drop the sprayer, trip over an object, or otherwise momentarily lose control of the sprayer while it is operating, the spray could be emitted in an unwanted and potentially harmful direction. Additionally, the rotary type of actuator does not provide control over the water pressure or the flow rate when the sprayer is turned on. Typically, this type of control must be obtained through a faucet or the like that regulates the water entering the hose.